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Effect of titanium content on the porosity and hardness of cu-ti-tic composite sintered by abnormal glow discharge

Abstract:

Copper metal matrix composites reinforced with TiC 1 % (%w/w) and titanium mass with fractions of 10 %, 15 % and 20 % were synthesized and characterized in order to evaluate the porosity in the material generated by the presence of titanium and material hardness. The MMC’s were manufactured by powder metallurgical route that included: mechanical and ultrasonic mixing of Cu-Ti-TiC in liquid suspension of 2-propanol, following by drying with subsequent uniaxial cold compaction at 400 MPa. Sintering by abnormal glow discharge at 850 °C in 10 % nitrogen and 90 % argon atmosphere; sintering time of 30 minutes and later cooling. Sintered samples were characterized by X-ray diffraction to determine the material phases. The morphological and compositional characterization were performed by scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). Porosity in green and sintered conditions were estimated by digital image analysis. As a result, in the green samples were evidenced a porosity in the range between 5,2% and 7,21% with the three fractions of Ti. The sintered samples value close to 13,6% were obtained with concentrations of 20% of Ti. The X-ray diffraction analysis showed the majority presence of the Cu3Ti and CuTi2 phases at 850 °C. The results by SEM and EDS exhibited the distribution of titanium associated with diffusive phenomena during sintering process. The hardness data were determined with the use of Vickers microdurometer with a load of 100 gf, showing that the presence of higher titanium content had influenced the hardness due to the formation of intermetallic phases, increasing its values up to 454 HV.